1. Field of the Invention
The present invention relates to a method for automatically determining heart valve damage and a device for performing the same and, more particularly, to a method and device for automatically determining and judging heart valve damage.
2. Description of Related Art
The heart is an important organ of the human body, and operates all the time. A heart with a small problem badly affects the health of the human body. A clear description of the heart is difficult because it is a very complicated organ. Therefore, the measurement of heart tones is still the most common method used by doctors in clinical diagnosis of the heart status.
The heart pulsation results in flow and circulation of the blood. There will be changes in tissue form and fluid mechanics during the pulsation period. Sounds emitted due to these changes can be heard by using a stethoscope. These sounds are called heart tones. Heart murmurs are caused by turbulent flow of the blood. They can be divided into the systolic period, the diastolic period and the sustaining period according to the occurrence time. They can also be divided into the aortic valve, the pulmonary valve, the tricuspid valve and the mitral valve according to the diagnosis positions. A valve is like a door for controlling the blood to flow in a certain direction. For instance, the aortic valve is located between the left ventricle and the main artery, and controls the blood supply of the whole human body. For a patient with a narrow aortic valve, there will be a pressure difference between the left ventricle and the main artery when the heart contracts. The narrower the aortic valve, the larger the pressure difference. A doctor can thus find the heart murmur of the systolic period.
The heart tones can be divided into a first heart tone, a second heart tone, a third tone and a fourth heart tone. The first heart tone occurs at the initial stage when the heart contracts, and includes two components caused by the closure of the mitral valve and the tricuspid valve. The second heart tone occurs at the last phase when the heart contracts, and also includes two components caused by the aortic valve and the pulmonary valve. The third heart tone occurs at the initial stage when the heart expands. The fourth heart tone occurs at the last phase when the heart expands. The first and second heart tones are sounds generated when the valves close and are thus easy to observe. The third and fourth heart tones are less apparent and thus difficult to observe. Abnormal sounds, sounds other than these four heart tones, are viewed as heart murmurs. These heart murmurs represent symptoms of heart diseases including valve stenosis, valve regurgitation, valve cracks, or other defects in structure.
Therefore, the heart tone diagnosis is an important tool for a doctor to determine the heart status. A series of stethoscopes have been developed to help doctors determine the heart status. For example, the US. Pat. App. No. 20030072457 discloses an electronic stethoscope, which provides three operation modes. The first operation mode only filters out the physiologic sounds of the heart. The second operation mode only filters out the physiologic sounds of the lung. The third operation mode enhances the observation of abnormal heart tones through comparison of normal and abnormal heart tones at different amplification ratios. This electronic stethoscope, however, does not automatically help the doctors analyze the damage of heart valves.
U.S. Pat. No. 4,619,268 discloses an esophageal stethoscope and vital signs monitoring system, which can discriminate the heartbeat sounds and breath sounds of the lung and then calculate out the heartbeat rate and the breath rate of the lung for monitoring the vital signs of a patient. This esophageal stethoscope and vital signs monitoring system, however, also does not automatically help the doctors analyze the damage of heart valves.
The above conventional stethoscopes can't automatically help the doctors to analyze the damage of heart valves. The determination of heart tones still depends on the subjective judgment of a doctor, and is thus subject to environmental and artificial influences such as the doctor's age, hearing sensitivity, and the training degree of the auscultation skill. This problem may cause erroneous judgment of the damage of the heart valves.